1. Field of the Invention
This invention relates to a method and system for route determination and a method and system for warning a driver of a vehicle of potential problems along a route.
2. Related Art
Navigation devices function to find optimal driving routes. Frequently, specific user-defined preferences are used in determining an optimal driving route. Such preferences can include finding the shortest or fastest route or avoiding ferries or highways. Identifying a fastest route is typically based upon road segment data, such as road segment length and speed limits for various types of road segments. Other parameters, are often not considered, such as the characteristic travel speed of the user's particular vehicle type, whether it be a car, bus, truck or some other vehicle.
Further, additional parameters, such as road restrictions can be of great importance in determining an optimal route. Such road restrictions may be relevant to all vehicles or only to certain vehicle types. For example, one-way restrictions impose the same limitations for all vehicles and these can be routinely taken into account in route determination by navigation devices. Other road passage restrictions may be applicable only to certain vehicles and these are not routinely considered by navigation devices. Such road passage restrictions can include, vertical clearance, horizontal clearance, roadway curvature radius, lane width and weight restriction of a road segment.
Moreover, parameters related to user preference, vehicle limitations or road passage restrictions can in some instance lie outside a range that might be considered ideal, thus creating potential problems for travel along a given route. Nevertheless, currently available navigation devices do not warn the user of these potential problems.
Thus, there is a need for improved methods and systems for route determination and for warning a driver of potential problems along the determined route.